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在。http://www.proftpd.org/docs/faq/proftpdfaq-4.html找到点线索

4.3 Unable to bind to port/Address already in use
0.0.0.0 is INADDR_ANY, which means to bind to any interface. The "address in use" will normally mean that something has already bound to that address.

Under linux it is possible to run

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fuser -n tcp 21
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to get the PID of the process currently bound to port ProFTPD is configured to run as.

The most common cause is that ProFTPD is configured standalone and inetd is still configured for port 21. Comment out the line starting "ftp" in /etc/inetd.conf and restart (killall -HUP inetd or something similar should do the trick) and try again.

不知道该如何处理，在 red hat linux 7.2 下，根本就没有 inetd.conf 这个文件。。

　　　　　　

RH7.2用的是xinetd　　　　　　

是的，好象 在 /etc/xinted.d 目录下有很多启动文件，包括：

wu-ftpd